The present invention relates to a stage control method for holding an object and a stage system using the stage control method. Particularly, the invention relates to a charged particle beam apparatus such as an electron microscope, an ion beam machining/observation apparatus, and the like.
In recent years, integration of semiconductor products has been improved more and more and higher definition of a circuit pattern thereof has been required. Various inspection means for the purpose of quality control and a yield increase have been used in a sample such as a wafer on which the circuit pattern is formed. For example, there is a SEM type inspection apparatus using an optical type inspection apparatus or a scanning type electron microscope (SEM) for inspecting foreign matters or defects of the wafer by applying light. Furthermore, a scanning type electron microscope (hereinafter, referred to as a length measurement SEM) for measuring a dimensional accuracy of the circuit pattern by applying a charged particle beam, a scanning type electron microscope (hereinafter, referred to as a review SEM) for evaluating the defects or the foreign matters by applying the charged particle beam and imaging defects of the circuit pattern or adhered foreign matters at a high magnification, and the like are also used. These apparatuses are collectively referred to as an inspection apparatus.
A stage used in such an inspection apparatus has a general configuration in which an X guide rail is attached to a base to guide an X table in an X-direction, the X table is mounted on the X guide rail, a Y table capable of moving in a Y-direction is further mounted on the X table, and a chuck holding a sample is mounted within a vacuum chamber. In such a stage, in the related art, a combination of a ball screw and a rotary motor is used as an actuator that is a driving source, but in recent years, a case where a linear motor of which a structure is simple and maintenance is also easy is used has been increased.
In order to continuously observe a plurality of positions of the wafer, it is necessary to move the stage and perform positioning of the wafer. In this case, if running of the stage is continued, a temperature of the stage is changed by heat generation of the linear motor. If the temperature of the stage is changed, a positioning accuracy of a position of the stage is degraded due to deformation, expansion, and the like of the table. Furthermore, if a difference in the temperature between the stage and the wafer that is transported is great, defects that a pattern cannot be positioned in a desired position may occur due to thermal expansion of the wafer during the observation.
Regarding such a problem described above, an exposure apparatus in which “heat is generated in a motor bypassing at least a current to the motor smaller than an excitation current required for driving the motor after a stage is stopped, and thereby a temperature is controlled in a state where a stage 11 is neither heated nor cooled” is disclosed in JP-A-2004-111684.
An electron beam drawing apparatus in which “a sample stage is operated during a certain period of time until a temperature of the sample stage becomes a set reference temperature or more”, that is, the stage is moved and is idling during a period of non-operation of the apparatus to prevent a decrease in a temperature in a state of the non-operation of the apparatus is disclosed in JP-A-2003-309062.